The present invention relates to a winch drive with an internally arranged planet gear and a motor for driving the winch drum being secured to the frame at one front end of the drum and wherein the drive shaft of the motor is drivingly connected to the driven input of the planet gear.
German printed patent application No. 3,042,479 discloses basically a winch drum of the type to which the invention pertains. The particular construction shown in that publication is disadvantaged by the fact that the driven input for the gear is run through hollow shafts to the side opposite the motor. Hollow drive shafts are needlessly expensive as compared with regular shafts and comparable gear ratios lead to a larger diameter of the gear so that planetary gears of this type are not always ameanable to be installed in conventional winch drums.
For economic reasons, winch drums should not have a diameter larger than is required in accordance with industry standards (see for example DIN No. 15020, FEM 9.661). If the winch drums have to be constructed with a, relatively speaking, larger diameter than necessary simply because the transmission gear has a large diameter the load on the gear as far as torque is concerned is inevitably higher and that in turn may require a larger speed reducing ratio under the assumption that the hub speed remains the same.
Another disadvantage of the arrangement shown in the above identified printed patent application is to be seen in that the combination, motor-transmission-clutch has to be arranged outside of the drum web and, therefore, requires appreciably more mounting space. In the case of compact lifting devices, this is another significant drawback.